For the 9th grade Physics, Chapter 9 "The kinetic model of matter"

2. Physical STATES OF MATTER
 The 5 States of Matter are:
◦ Solid
◦ Liquid
◦ Gas
* Plasma
* Bose-Einstein
Condensates

3. States of Matter
1. The molecules of solid are locked in a rigid structure
and can only vibrate. (Add thermal energy and the
vibrations increase.)
Some solids are crystalline, like table salt,
in which the atoms are arranged in a
repeating pattern. Some solids are
amorphous, like glass, in which the
atoms have no orderly arrangement.
Either way, a solid has definite volume and shape.

4. 2. A liquid is virtually incompressible and has
definite volume but no definite shape,
if you pour a liter of juice into several
glasses, the shape of the juice has
changed but the total volume hasn’t.
3. A gas is easily compressed. It has
neither definite shape nor definite
volume, If a container of CO2 is
opened, it will diffuse throughout the
room.

5. *A plasma is an ionized gas and is the
most common form of matter in the
universe, since the insides of stars are
plasmas.

6. KINETIC THEORY
Also known as
“The Kinetic (Particle) Model of Matter”
Kinetic Theory states that the tiny
particles in all forms of matter are in
constant motion.
 3 Principles of Kinetic Theory:
• All matter is made of tiny particles.
• These particles are in constant motion
• When particles collide with each other or the
container, the collisions are perfectly elastic.

7. * BOSE-EINSTEIN CONDENSATE
 Particles extremely close together
 Particles barely move
 Only found at extremely cold
temperatures
 Basically Bose-Einstein is a cold solid
 Lowest energy of the 5
states/phases of matter

9. Phase Changes
Evaporation: Liquid  Gas
Condensation: Gas  Liquid
Melting: Solid  Liquid
Freezing: Liquid  Solid
*Sublimation: Solid  Gas
*Examples of sublimation:
• Dry ice (frozen CO2) goes directly from the solid to the
gaseous state (it sublimates). This creates an eerie.
• Comets are very small objects containing frozen gases that
sublimate when the comet get close enough to the sun. This
creates the characteristic tail the can be millions of miles long.

11. Fluids
The term fluid refers to gases and liquids.
Gases and liquids have more in common with
each other than they do with solids, since gases
and liquids both have particles that are free to
move around. They are not locked in place as
they are in a solid. The hotter the fluid, the
faster its molecules move, and the more space
the fluid will occupy. Also, unlike solids, fluids
can flow.

12. Pressure & Freezing
For most liquids the freezing point increases if its
pressure is increased, i.e., it’s easier to freeze most
liquids if they’re subjected to high pressures. In order
to turn a liquids into a solid, the molecules typically
must get close enough together to form a crystal. Low
temps mean slow moving molecules that are closer
together, but high pressure can squeeze the molecules
closer together, even if they’re not moving very slowly.
Water is an exception to this because, due to its
molecular shape, it expands upon freezing. So,
squeezing water makes freezing it harder. The pressure
on ice due to a passing skater can actually melt a small
amount of the ice.

13. Pressure & Boiling
The lower the pressure on a liquid, the easier it is to make
it boil, i.e., as pressure increases, so does the boiling pt.
This is because in order for a liquid to boil, molecules need
enough kinetic energy to break free from the attraction of
the molecules around it. It’s harder for a liquid to vaporize
when subjected to high pressure, since gases take up more
space than liquids.
Water, for example, boils at temps below 100 ºC up in the
mountains where the air pressure is lower. It takes longer
to cook food in boiling water at high altitudes because the
boiling water isn’t as hot. In a vacuum water will boil at
any temp, since there is no pressure at the surface to
prevent the water from vaporizing. At high pressure water
boils at a high temp. In a pressure cooker water can
remain liquid up to 120 ºC, and the hotter water can cook
food faster.

14. Freezing of Solutions
The freezing point of a solution, such as salt water, is
lower than the freezing point for the solvent by itself,
e.g., pure water. The higher the concentration of the
solute, e.g. salt, the more the freezing point is lowered.
The reason it is more difficult to freeze a liquid when a
substance is dissolved in it is because the “foreign”
molecules or atoms of a solute interfere with the
molecules of the solvent as they’re trying to form a
crystalline structure.

16. boiling and evaporation
 Evaporation takes place only at the
surface of a liquid or solid, while boiling
takes place throughout
the body of a liquid.
 Boiling occurs at the
boiling temperature.
 Particles that have
“higher kinetic energy”
escape and become
vapor (gas).

18. Factors affecting the rate of
evaporation:

19. Boyle’s Law:
Robert Boyle in 1662 discovered
that “as pressure on a gas was
increased, its volume decreased”.
Boyle’s Law states that “if the
temperature of an ideal gas is held
constant, the pressure and volume
of a given amount of an ideal gas are
inversely proportional” (a given
amount of gas means a fixed mass
or number of molecules).

22.  Boyle's Law Formula is expressed symbolically as
Another way to express Boyle's Law Formula is
or
 Where:
 P is pressure of the gas
 V is volume of the gas
 k is a constant, and has units of force times distance

23. Boyle's Law Problems
 Question 1: A sample of gaseous nitrogen in a 65.0
L automobile air bag has a pressure of 700 mm Hg. If
this sample is transferred to a 25.0 L bag at the same
temperature. what is the pressure of the gas in the
25.0 L bag?
 Question 2: A sample of neon (Ne) occupies 4.00L at
a pressure of 5.00 × 104 Pa and a temperature of
273K. Determine the volume of the sample at
100KPa?
 Answers: (1) P1 = 1820 mm Hg, (2) V2 = 2 L

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kinetic-molecular-model-of-matter.html